Power down - no ses light.

[RWSDIESEL]

Many have been having problems with de-fueling as it is called, while towing or under load with no ses light afterwards.

Remedy,
Assuming the ses bulb is working in the dash upon first turning on the ignition.
When the ECU limits engine power it is generally for a reason and ses light on dash should illuminate, in most cases if ses light does not come on replace the ECU per GM.
It will probably take care of and fix the abnormal de-fueling problem to begin with.

[Texasoilman44]

Good morning all,

While we are on this subject, when this "power down" happens, is the quick fix simply to just turn the ignition off then back on, to be able to reset the fault so that you can continue on till you can have the ECU replaced?

Best Regards,

Kevin

[hoot]

My experience has been this.

All of a sudden I lose power as if I've run out of fuel. There is a little there but not much. After slowing down for a few seconds, she comes back to life. No action required.

I want to point out that this occurred early on once while towing when my truck was 100% stock. I originally thought something was wrong with the trans but now I realize it was a de-power. I was towing a Full Size Chevy Blazer on a car trailer so it wasn't over loaded.

At this point with my truck, I attribute it to requiring a reflash but I want to wait and see when the latest codes become available.

RWSDIESEL,

In response to your statement about replacing the ECM due to no SES light. Are you a GM diesel technician? Is this coming from something in the tech info?
Thanks,

Mike

[ 03-28-2002: Message edited by: hoot ]</p>

[Steve Cole]

I work on the code in the ECU all day long and I can tell you all for a fact that you can go into defueling and NOT set the SES light. The code allows for this in several places. So if you go into defueling and don't get a SES light IT'S NORMAL!

[hoot]

Thank you Steve. I was a little worried there. Maybe you can enligten us a little on when and why de-fueling takes place without divulging any trade secrets? Mine will defuel at about 75-80 mph on propane, not under load, just cruising with moderate acceleration from 70-80 mph. What is it thinking?

[ 03-28-2002: Message edited by: hoot ]</p>

[RWSDIESEL]

Last week a customer came in with a defueling problem, (ECM limits fuel delivery)while towing, as explained by hoot "All of a sudden I lose power as if ive run out of fuel" we did not tell this customer "it is NORMAL" and send him on his way, instead we were as concerned about this problem, as was the customer coming in to us for this problem in the first place.
A HP tech II was connected and 2 DTC (diagnostic trouble codes) were present, 1 of which was P0238 overboost, another transmission related. Customer stated malfunction indicator lamp (MIL) or SES never came on at anytime before or after failure. We disconnected boost sensor, MAF, and a few other vital sensor connections and sure enough no ses light, but DTC codes set in ECU.
The ses light worked properly when the key was turned to the run position without the engine running.
We replaced ECU, ses light functioned correctly correlating with the set DTC's\
Have not heard back from this customer since.

[RWSDIESEL]

HOOT,
As you are most likely aware propane increases combustion temperatures, spins turbo faster, resulting in increased boost compaired to no propane at that paricular throttle position.
The ECU continuously samples the actual amount of boost pressure that should be present for the given throttle position range, if the actual boost pressure is not in predicted range for 30 seconds DTC P0234 will set, the ECM will limit fuel delivery.
P0234 is usually associated with non wide open throttle positions.

[hoot]

RWS,

Good stuff. I have had my SES come on before. Once when it went into full limp mode. Didn't go out till the next day. On de-fueling, it used to go on but doesn't anymore.

So what is the deal hear anyway? You think the SES will come on if I fart?

[mackin]

Hoot,

Hay HOOT maybe depends on how many beers you drank and what you eat...........LOL I'll bet a six pack of your favorite blend and a bowl of chili might throw it into LIMP mode.....LOL WE may have another potential problem here.........Keep us posted dude......



MAC :D :D :D

[hoot]

Re-located my propane line last night.

Previously it entered through the grommet where the filter minder normally resides (per installation instructions).

When I had the air cleaner off doing my aftermarker fuel filter add-on, I took a closer look at where the hose actually sits in there.

It's not directly in front of the MAF sensor but it is in front and below. Air comes in from below so this hose could well be causing turbulance in front of the sensor.

I pulled the hose out, put the filter minder back in and drilled a hole in the plastic turbo intake pipe just small enough for a 1/4" push on style brass fitting to self-thread. It went in real nice and firm and since it's tapered thread, the further in the tighter.

Truck runs better now with propane off (not better than with lp on ;) )and has more getup. I really think that hose was messing up the airflow over the MAF sensor which in turn was messing with computer/fuel.

Last night and this morning I tried to get it to defuel. So far.... looks good.

It ain't over yet. Need a good week before I can say it's fixed and that don't mean a cold winter morning won't cause it. I guess the final answer will be this fall/winter.

[a64pilot]

Hoot said,
"So what is the deal hear anyway? You think the SES will come on if I fart?"
Only if you fart into the intake. The high methane content may cause boost to exceed the expected amount. :D :D :D

[breeze hotshot]

Hey Group
When you say power down do you lose all power
or just a noticeable decrease ?
My power seems to change for no good reason
This is only when hauling.

[jcummins]

I've had the power down three times. All three times I was running 55-65 mph, and not hauling. Also all three times it was raining. I'm juiced 90hp version. All three times it recovered on it's own in 5-10 seconds. First vehicle I've ever had that did something like this, and I don't consider it NORMAL. If it shut off at the wrong time, and depending on traffic, you may have quite a problem on your hands. Don't like it plain and simple.

[mackin]

jcummins

There has been some issue s regarding the Juice doing exactly what your referring to .... Update to the latest version if you have not yet .....

Assuming you take the Juice of and problem disappears,it would be unrelated to what Hoot is experiencing as I understand it .....


Edge as I understand is looking into it, unfortunately you are of a minority on this problem....

Chevyhdman is experiencing the same problem ..... Edge replaced his box with a 4.61 no timing .... The problem is gone but he describes it as gutless .... Sorta like the 3.61sucky version, if you have been following the Edge version releases .... I haven't gone for a ride with him, yet .....Or we haven't lined them up, yet .....

Call Edge they'll work with you to resolve......

MAC

[GMC-2002-Dmax]

MAC,

Are you saying you know of a spot we could get together??? :eek: :eek:

Line up you say. I think I need to see if I can defuel my truck and you and Bill and the other CT members should all be there for moral support if something should break. :D

Name the place. Weekends look pretty good.

GMC ;)

[dmaxalliTech]

FWIW, ses light will only come on for maf, map, overboost after two consecutive drive cycle failures. Will only come on immediatly if emissions damaging. Type B will turn light on after two trips, type a will come on and flash then stay on steady

[GMCTRUCK]

A CT get together at a watering hole sounds great. My TST box is currently getting reflashed ;) so I'm sure I'll be able to break something. :D

[ 04-30-2003: Message edited by: GMCTRUCK ]</p>

[hoot]

I think mines cured.... finally.

All I did was relocate the lp hose and add a 2 micron post OEM fuel filter.

Went on a 60 mile trip to Allentown... you all know where that is don't ya? to pick up my new Hummer rims. Truck runs better than it ever has. Absolutely no doubt that it stronger and smoother. I'm scratching my head on this one. I could do an experiment and shove the extra piece of hose I have in the intake box and see if it acts up again.

Rims are gorgeous. Looks like my center caps fit perfectly.